'The Flash': EP Aaron Helbing Previews 'Attack On Central City'

Grodd is bringing an army to Central City in Tuesday night's "The Flash," and the multiverse team will have to band together to stop them.

The meta-gorilla will use the powers of recent Team Flash friend Gypsy (Jessica Camacho) to reach Earth 1, setting up an epic match-up between Grodd, his army and our heroic gang.

Flash, Kid Flash, Jesse Quick, H.R. Wells, Harrison Wells, Iris West, Joe West, Caitlin Snow, Cisco Ramon/Vibe and Julian need a creative idea to stop them. For more about what we can expect in the second of the Grodd two-parter, airing at 8/7c on The CW, AccessHollywood.com hopped on the phone with Executive Producer Aaron Helbing.

AccessHollywood.com: Tell me about Accelerated Man in this episode [Note: he's featured in the promo photos]. Is he a friend or foe of Team Flash?Aaron Helbing: He's more of an Easter Egg. We don't necessarily have plans to use Accelerated Man. We wanted to see Cisco kind of appeal to Gypsy. … We always try to make every scene as interesting as we can, and it just felt really cool to have it, and in a ... Central City/Grodd episode.

Access: So he's not around for very long then, if he's an Easter Egg? That's usually like a snippet, right?Aaron: Yeah, just a snippet. I mean, it could be interesting to maybe do an Accelerated Man episode, but we just don't have plans at the moment.

Access: I wanted to know about Gypsy and whether or not she's a willing participant in Grodd's plans to go back to Central City or if she's sort of being strong-armed into doing this? Does he have some leverage over her?Aaron: Well, as we saw in Episode 13, Grodd and Solovar have the ability to take over other people and so you'll learn that Grodd has taken over Gypsy -- but for a reason. And, the team will quickly realize when Gypsy attacks that the only way she would have attacked them is if she was under someone's control and that's a clue that they get to learn that Grodd is on Earth 1.

Access: How is that going to impact Cisco because obviously he has developed a connection with [Gypsy in a previous episode]?Aaron: He doesn't fault her for attacking. He's a little surprised by it, but he quickly realizes she was under Grodd's control and … his main goal is to get her to help the team and selfishly further his relationship with her. But he doesn't think that she was guilty of attacking them of her own volition. He knows Grodd's abilities and how powerful he is and how it can take over anyone. And you'll see Grodd takeover someone else close to the team and how that impacts Barry and Iris and the team.

Access: [Trying to save Iris] comes up at different points in the episodes. It's something they're figuring out as [they go along]. Is that pretty strong drive in this episode as well? Obviously … the gorillas were in the future headlines.Aaron: Yeah, I mean, Barry thinks when they escaped Earth 2 and Gorilla City that all is well in the world. But, he'll quickly realize all is not well in the world once Gypsy comes and attacks. And so, he's starting to get frustrated because he's realizing that the future is essentially set at the moment and no matter what he tries to do, no matter how many things he does or how many Gorillas he defeats, it's not changing the future and that's really frustrating him.

Access: I want to know about the Gorilla attack on Central City. Obviously that would be very expensive to do in a second episode with all those [special effects-made] gorillas, but I imagine you guys are probably pulling out all the stops still. What kind of a situation are we going to see gorilla-wise in Central City. What's the scope of it? Aaron: I would say it's pretty epic. It's not an arena, but you'll see Grodd with his legion army of gorillas as they're approaching Central City, and you'll see Flash and Kid Flash and Jesse Quick take on gorillas, you'll see Flash take on Grodd, you'll see Solovar. We planned on doing a two-part Grodd episode, so you just have to plan accordingly when you're going to do these massive episodes. So that's kind of what we do because we plan – 'OK, we need to build up to this, from a fiscal standpoint.' That's pretty much what we do, and then we entrust a lot to Encore and Armen Kevorkian, who's our VFX supervisor, and they just continue to blow us away.

Access: Do we get to see more of H.R. and [Harry] talking to each other in this episode? What fun challenge to give to Tom Cavanagh.Aaron: Oh yeah, you'll definitely see them. It's a lot of fun. I mean, Harry being gruff and H. R. -- he wants everybody to like him. So they kind of come at loggerheads with each other, but Harry will realize that there's a reason why the team has kept H.R. around. Regardless of being a genius, he provides a spark that Harry provided in Season 2, and so there has to be a mutual respect between them.

Access: I've got to ask you about Caitlin and Julian. Are you guys moving towards something of a romantic nature between those two? Clearly they have chemistry, but she has some serious things to deal with, with her powers. So, [I] was curious if you could hint at what's next for those two.Aaron: Well, I think they're -- just like any pair of friends that start to have feelings for each other, they're navigating a minefield. This is on a heightened level because Julian was Dr. Alchemy and created a lot of metahumans and Caitlin is struggling to have any control over her powers, and she doesn't want to go down the slippery slope where she becomes Killer Frost, so it's kind of a balancing act between the two. And that's kind of the way we're playing it is, they have feelings for each other -- more so, I would say he has more feelings for her at the moment, based on her past and just dealing with what happened with Zoom and what happened with Ronnie. So they're kind of tap dancing, I would say. But you know, they'll get closer by the end of this episode, and that will kind of launch them further into the future.